1. Field of the Invention
The invention relates generally to articulators and correlators for registering upper and lower dental casts and more specifically to disposable articulators that can be permanently attached to the dental casts and inexpensive enough to accompany them from the dental lab to the client doctor and then to be disposed after use.
2. Description of the Prior Art
The comprehensive treatment of dental patients includes the casting and modeling of both the patient's teeth and the full range of occlusal and masticatory registration characteristics. Good models allow the doctor to work out the procedures and prosthetics that will ultimately be necessary to treat the condition with a minimum of personal visits by the patient to the doctor's office.
Ronald E. Huffman describes an inexpensive throw away articulator for dental models in U.S. Pat. No. 4,382,787, issued May 10, 1983, which patent is incorporated herein by reference. Upper and lower dental model casts are prepared with a flat face and slot at the rear of each cast. A hinged articulator is attached on opposite ends to each of the casts by anchors that are glued into each of the slots. The articulator hinge is connected to each anchor by a snap in ball joint that allows the proper spatial relationship between the upper and lower casts to be adjusted. Such ball joints may be filled with glue to fix the adjustment once made. In practice, such articulators are not as stiff and rigid as could be desired, thus the registration changes with even modest flexing and twisting.
A dental model articulator that appears better able to resist flexing and twisting is described by Farnor, Jr., et al., in U.S. Pat. No. 5,482,460, issued Jan. 9, 1996, and incorporated herein by reference. A wide hinge has top and bottom vertical channels on its front face that receive mating ears from the top and bottom anchors attached to the rear slots in the top and bottom dental model casts. A technician holds the casts in occlusion and presses the anchor ears into their respective hinge channels filled with fast setting glue. After a few seconds, the articulator becomes fixed with the proper occlusion and the hinge can be opened to manipulate the casts.
Alan M. Westdyk describes in U.S. Pat. No. 5,360,337, issued Nov. 1, 1994, a dental articulator in which the cast anchors are placed in the rear wall of the tray molds for the dental casts and are partially embedded. After curing and setting, the dental casts and anchors are removed from the tray molds and assembled to the articulator.
The prior art has not fully satisfied the need to have high performance articulator systems that maintain their occlusal and masticatory registration with ordinary handling and that can offer the advantage of costs that are low enough to make such articulators disposable after use.